German Patent Application No. 39 39 548.0 discloses a fuel injection system for internal combustion engines that works with a wall-film model. In addition to a basic injection signal, a wall-film signal is generated that is dependent on operating parameters. Moreover, a control-factor signal is generated, which given a transient operation of the internal-combustion engine, takes into account the change in the wall film over time.
Another known system is described in German Patent Application No. 40 40 637. This system stores in memory the wall-film quantity as well as a control-factor signal. These stored values can be adapted to the modified operating conditions of the internal combustion engine during the lifetime of a motor vehicle.
The prior art describes a number of measures for transition compensation, in particular for acceleration enrichment, with which one attempts to control this transition condition more precisely and effectively. An example of this is German Patent Application No. 30 42 246, which corresponds to U.S. Pat. No. 4,440,136. Other prior art relating to transition compensation are German Patent Application No. 36 03 137, World Patent Application No. WO 90/064 28, German Patent Application No. 36 36 810, which corresponds to the U.S. Pat. No. 4,852538, and German Patent Application No. 40 06 301.
Prior art that provides a fundamental understanding of the wall-film model is SAE paper 81 04 94 "Transient A/F Control Characteristics of the Five Liter Central Fuel Injection Engine," by C. F. Aquino.
The present invention provides an improved method for controlling fuel injection during acceleration and deceleration.